Touch-control detection circuit and display apparatus

Abstract

Provided in the present application are a touch-control detection circuit and a display apparatus. The touch-control detection circuit comprises a piezoelectric ceramic sensor, an electrically conductive member, a detection circuit, a compensation circuit and a controller, wherein the detection circuit is electrically connected to both the electrically conductive member and the piezoelectric ceramic sensor; the compensation circuit is connected to the piezoelectric ceramic sensor; an input terminal of the controller is connected to the detection circuit, and an output terminal of the controller is connected to the compensation circuit; and the controller is configured to receive a detection signal in digital form, acquire a vibration signal and / or a pressure signal of a touch-control cover plate on the basis of the detection signal, and control the compensation circuit to output a compensation charge amount to the piezoelectric ceramic sensor.

Description

Touch detection circuit and display device

[0001] This application claims priority to Chinese Patent Application No. CN202411626009.3, filed on November 14, 2024, entitled “Touch Detection Circuit and Display Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of sensor technology, and more specifically, to a touch detection circuit and a display device. Background Technology

[0003] In the relevant technical field, when installing piezoelectric ceramic sensors onto touch cover plates, adhesive is required for bonding. However, the long curing time of the adhesive takes a lot of time and consumes a lot of tooling and fixture time, resulting in low production efficiency of display devices.

[0004] In related technical solutions, insulating tape is often used to pre-fix the piezoelectric ceramic sensor and the touch cover plate. However, this results in poor anti-interference ability of the touch detection circuit and poor detection accuracy of the piezoelectric ceramic sensor. Summary of the Invention

[0005] This application provides a touch detection circuit and a display device. The controller can periodically acquire digital detection signals through the detection circuit and output compensation charge to the piezoelectric ceramic sensor through the compensation circuit, so that the charge of the piezoelectric ceramic sensor is equal to the preset charge, thereby restoring the piezoelectric ceramic sensor to its initial state. This can increase the measurement range of the touch detection circuit, thereby increasing the applicability of the touch detection circuit, and make the change in the charge of the piezoelectric ceramic sensor more accurate, thereby improving the accuracy of judging the touch point and the material of the touch object.

[0006] This application provides a touch detection circuit, which includes a piezoelectric ceramic sensor, a conductive element, a detection circuit, a compensation circuit, and a controller. The piezoelectric ceramic sensor is disposed on a touch cover plate. The conductive element covers the piezoelectric ceramic sensor and is electrically connected to it. The detection circuit is electrically connected to both the conductive element and the piezoelectric ceramic sensor. The compensation circuit is connected to the piezoelectric ceramic sensor. The input terminal of the controller is connected to the detection circuit, and the output terminal of the controller is connected to the compensation circuit. The detection circuit acquires the charge change of the piezoelectric ceramic sensor and outputs a digital detection signal. The compensation circuit outputs a compensation charge to the piezoelectric ceramic sensor so that the charge of the piezoelectric ceramic sensor is equal to a preset charge. The controller receives the detection signal and, based on the detection signal, acquires the vibration signal and / or pressure signal of the touch cover plate. The controller also controls the compensation circuit to output a compensation charge to the piezoelectric ceramic sensor based on the detection signal.

[0007] Based on the above embodiments, when a user touches the touch cover, the piezoelectric ceramic sensor converts the vibration signal and pressure signal into the change in charge between the positive and negative piezoelectric layers. The detection circuit acquires the change in charge and converts it into a digital detection signal. The controller can acquire the vibration signal and / or pressure signal of the touch cover based on the detection signal, and thus acquire the touch point and the material of the touch object based on the vibration signal and pressure signal.

[0008] Furthermore, after the controller acquires the detection signal, it can control the compensation circuit to output a compensation charge to the piezoelectric ceramic sensor, so that the charge between the positive and negative piezoelectric layers of the piezoelectric ceramic sensor is equal to the preset charge, thereby restoring the piezoelectric ceramic sensor to its initial state. This allows the piezoelectric ceramic sensor to convert the vibration and pressure signals into charge for the second time, which can improve the accuracy of the charge conversion of the piezoelectric ceramic sensor and the accuracy of the detection signal acquired by the controller, thereby improving the accuracy of the judgment of the touch point of the touch cover and the material of the touched object.

[0009] Furthermore, because the controller can periodically acquire detection signals and output compensation charge to the piezoelectric ceramic sensor through a compensation circuit, the charge of the piezoelectric ceramic sensor is made equal to the preset charge, thus restoring the piezoelectric ceramic sensor to its initial state. Therefore, the measurement range of the touch detection circuit can be increased, thereby expanding the applicability of the touch detection circuit.

[0010] Furthermore, the use of conductive components to form a shielding layer can improve the piezoelectric ceramic sensor's resistance to electromagnetic interference, thereby improving the detection accuracy of the piezoelectric ceramic sensor, simplifying the circuit design of the touch detection circuit, and reducing the cost of the touch detection circuit.

[0011] In some embodiments, the piezoelectric ceramic sensor includes a conductive substrate, a positive piezoelectric layer, a ceramic body, a negative piezoelectric layer, and an insulating layer. The conductive substrate is used to bond with a touch cover plate. The positive piezoelectric layer is disposed on the side of the ceramic body away from the conductive substrate. The insulating layer at least covers the side of the positive piezoelectric layer away from the ceramic body. The negative piezoelectric layer is disposed on the side of the ceramic body facing the conductive substrate and is connected to the conductive substrate. A portion of the conductive element covers the side of the insulating layer away from the positive piezoelectric layer, and another portion of the conductive element covers the conductive substrate and is electrically connected to the conductive substrate. The detection circuit is electrically connected to the conductive element and the positive piezoelectric layer respectively, and the compensation circuit is connected to the positive piezoelectric layer.

[0012] Based on the above embodiments, conductive components can be used to bond the conductive substrate and the touch cover to position the conductive substrate and the touch cover. This reduces the probability of the conductive substrate moving relative to the touch cover after the tooling fixture is removed, improves the efficiency of the tooling fixture, and thus improves the production efficiency of the display device.

[0013] By applying an insulating layer to the side of the positive piezoelectric layer away from the ceramic body, and then completely covering the side of the insulating layer away from the positive piezoelectric layer with a conductive component, the contact area between the conductive component and the piezoelectric ceramic sensor can be increased, thereby improving the connection stability between the conductive component and the piezoelectric ceramic sensor. This, in turn, improves the connection stability between the piezoelectric ceramic sensor and the touch cover, reducing the probability of the piezoelectric ceramic sensor moving relative to the touch cover.

[0014] In some embodiments, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive element; or, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive element through the negative piezoelectric layer; or, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive element through a conductive substrate.

[0015] In some embodiments, the detection circuit includes a charge integrating circuit, a non-inverting amplifier circuit, and an analog-to-digital converter circuit. The charge integrating circuit is connected to a conductive element and a positive piezoelectric layer to output a voltage signal. The input terminal of the non-inverting amplifier circuit is connected to the output terminal of the charge integrating circuit to amplify the voltage signal. The input terminal of the analog-to-digital converter circuit is connected to the output terminal of the non-inverting amplifier circuit, and the output terminal of the analog-to-digital converter circuit is connected to a controller to convert the amplified voltage signal into a digital detection signal.

[0016] Based on the above embodiments, when a user touches the touch cover, the piezoelectric ceramic sensor converts the vibration signal and pressure signal into the change in charge between the positive and negative piezoelectric layers. The change in charge is converted into a voltage signal by a charge integration circuit. The voltage signal is amplified by a non-inverting amplifier circuit and then converted into a digital detection signal by an analog-to-digital converter circuit, so that the controller can obtain the detection signal and thus obtain the touch point of the user touching the touch cover and the material of the touched object.

[0017] In some embodiments, the charge integrating circuit includes a first amplifier, a first capacitor, and a first resistor. The inverting input terminal of the first amplifier is connected to the positive piezoelectric layer, the non-inverting input terminal of the first amplifier is connected to a conductive element, and the non-inverting input terminal of the first amplifier is used to connect to a power supply. The positive power supply terminal of the first amplifier is used to connect to a power supply, the negative power supply terminal of the first amplifier is grounded, and the output terminal of the first amplifier is connected to the output terminal of the charge integrating circuit. The first plate of the first capacitor is connected to the inverting input terminal of the first amplifier, and the second plate of the first capacitor is connected to the output terminal of the first amplifier. The first end of the first resistor is connected to the first plate of the first capacitor, and the second end of the first resistor is connected to the second plate of the first capacitor.

[0018] Based on the above embodiments, the first resistor provides input bias current to the first amplifier to ensure its normal operation. When abnormal charge enters the first capacitor, the first capacitor can discharge through the first resistor to eliminate the influence of the abnormal charge on the voltage across the first capacitor, thereby reducing the impact of the abnormal charge on the output signal of the first amplifier and improving the accuracy of the voltage signal at the output of the first amplifier. The first capacitor is an integrating capacitor and forms an analog integrator with the first amplifier. The analog integrator can transfer and accumulate the charge output by the piezoelectric ceramic sensor into the first capacitor, thus realizing the input charge and output voltage signal. The voltage signal at the output of the first amplifier is linearly correlated with the change in charge between the two plates of the first capacitor.

[0019] In some embodiments, the charge integration circuit further includes a second resistor, the first end of which is connected to the positive piezoelectric layer, and the second end of which is connected to the inverting input of the first amplifier.

[0020] Based on the above embodiments, the second resistor is used to divide the charge entering the inverting input terminal of the first amplifier to limit the bandwidth of the charge integration circuit, and can adjust the phase of the charge integration circuit, thereby improving the loop stability of the charge integration circuit.

[0021] In some embodiments, the non-inverting amplifier circuit includes a third resistor, a fourth resistor, a second amplifier, and a fifth resistor. The first terminal of the third resistor is connected to the input terminal of the non-inverting amplifier circuit; the first terminal of the fourth resistor is used to connect to a power supply; the non-inverting input terminal of the second amplifier is connected to the second terminal of the third resistor, the inverting input terminal of the second amplifier is connected to the second terminal of the fourth resistor, the positive power supply terminal of the second amplifier is used to connect to a power supply, the negative power supply terminal of the second amplifier is grounded, and the output terminal of the second amplifier is connected to the output terminal of the non-inverting amplifier circuit; the first terminal of the fifth resistor is connected to the inverting input terminal of the second amplifier, and the second terminal of the fifth resistor is connected to the output terminal of the second amplifier.

[0022] Based on the above embodiments, the voltage signal output by the charge integration circuit is amplified by a non-inverting amplifier circuit composed of a third resistor, a fourth resistor, a second amplifier, and a fifth resistor, so as to improve the accuracy of the detection signal acquired by the controller.

[0023] In some embodiments, the non-inverting amplifier circuit further includes a second capacitor, the first plate of which is connected to the inverting input terminal of the second amplifier, and the second plate of which is connected to the output terminal of the second amplifier.

[0024] Based on the above embodiments, the second capacitor can present low impedance to high-frequency noise, and the amplification factor of high-frequency noise can be selectively reduced by the fifth resistor. This allows the in-phase amplifier circuit to amplify low-frequency signals better, thereby improving the accuracy of the detection signal acquired by the controller.

[0025] In some embodiments, the non-inverting amplifier circuit further includes a sixth resistor, the first end of which is connected to the output of the second amplifier, and the second end of which is connected to the output of the non-inverting amplifier circuit.

[0026] Based on the above embodiments, the sixth resistor can limit the current of the voltage signal output to the output terminal of the second amplifier, thereby reducing the probability of the controller being burned out by a large current, thus enabling the controller to have a longer service life, and consequently enabling the touch detection circuit to have a longer service life.

[0027] In some embodiments, the analog-to-digital converter circuit includes a first comparator, the non-inverting input of the first comparator being connected to the input of the analog-to-digital converter circuit, the inverting input of the first comparator being connected to a power supply, and the output of the first comparator being connected to the output of the analog-to-digital converter circuit.

[0028] Based on the above embodiments, the amplified voltage signal output from the output terminal of the second amplifier can be converted into a digital signal using the first comparator, so that the controller can receive the corresponding detection signal and thereby obtain the touch point of the touch cover and the material of the touch object.

[0029] In some embodiments, the compensation circuit includes a Schmitt trigger, the input of which is connected to the input of the compensation circuit, and the output of which is connected to the output of the compensation circuit.

[0030] Based on the above embodiments, after the controller receives the detection signal, it sends a compensation signal to the input terminal of the Schmitt trigger according to the detection signal, so that the Schmitt trigger outputs a compensation charge to the piezoelectric ceramic sensor according to the compensation signal, so that the charge of the piezoelectric ceramic sensor is equal to the preset charge, thereby restoring the piezoelectric ceramic sensor to its initial state.

[0031] In some embodiments, the compensation circuit further includes a seventh resistor, the first end of which is connected to the output of a Schmitt trigger, and the second end of which is connected to the output of the compensation circuit.

[0032] Based on the above embodiments, by using the seventh resistor, the probability of a large current entering the piezoelectric ceramic sensor can be reduced, thereby reducing the probability of damage to the piezoelectric ceramic sensor and enabling the piezoelectric ceramic sensor to have a longer service life.

[0033] This application also provides a display device, which includes a housing, a display module, a touch cover, a circuit board, and a touch detection circuit. The display module is connected to the housing; the touch cover and the display module are stacked on the housing; the circuit board is disposed inside the housing; and the touch detection circuit is disposed on the touch cover and electrically connected to the circuit board. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 is a schematic diagram of the structure of a display device in one embodiment of this application;

[0036] Figure 2 is a cross-sectional view of the touch cover, piezoelectric ceramic sensor and conductive component in one embodiment of this application.

[0037] Figure 3 is a cross-sectional view of the touch cover, piezoelectric ceramic sensor, thermal insulation structure and conductive component in another embodiment of this application.

[0038] Figure 4 is a schematic diagram of the frame structure of the touch detection circuit in one embodiment of this application;

[0039] Figure 5 is a circuit diagram of a touch detection circuit in one embodiment of this application.

[0040] Explanation of reference numerals in the attached drawings: 1. Display device; 11. Housing; 12. Touch cover; 2. Touch detection circuit; 21. Piezoelectric ceramic sensor; 211. Conductive substrate; 212. Positive piezoelectric layer; 213. Ceramic body; 214. Negative piezoelectric layer; 215. Insulating layer; 216. Insulating sealant; 22. Conductive component; 23. Thermal insulation structure; 24. Detection circuit; 241. Charge integration circuit; 242. In-phase amplifier circuit; 243. Analog-to-digital converter circuit; 25. Controller; 26. Compensation circuit; R1. First resistor; R2. Second resistor; R3. Third resistor; R4. Fourth resistor; R5. Fifth resistor; R6. Sixth resistor; R7. Seventh resistor; C1. First capacitor; C2. Second capacitor; A1. First amplifier; A2. Second amplifier; A3. First comparator; A4. Schmitt trigger. Embodiments of the present invention

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0042] In the relevant technical field, when installing piezoelectric ceramic sensors onto touch cover plates, adhesive is required for bonding. However, the long curing time of the adhesive takes a lot of time and consumes a lot of tooling and fixture time, resulting in low production efficiency of display devices.

[0043] In existing technologies, insulating tape is often used to pre-fix the piezoelectric ceramic sensor and the touch cover plate. However, this leads to a more complex touch detection circuit and higher production costs for the display device. In this embodiment, the insulating tape is replaced with a conductive component, and this conductive component forms a shielding layer with the conductive substrate. Combined with the touch detection circuit, this improves the piezoelectric ceramic sensor's resistance to electromagnetic interference, thereby enhancing its detection accuracy. It also simplifies the circuit design of the touch detection circuit, reducing its cost and ultimately lowering the cost of the display device.

[0044] Please refer to Figures 1-4. This application provides a display device 1, which includes a housing 11, a display module, a touch cover 12, a circuit board, and a touch detection circuit 2.

[0045] The housing 11 is used to mount the display module, touch cover 12, circuit board, and touch detection circuit 2, and can protect the display module, touch cover 12, circuit board, and touch detection circuit 2 to reduce the probability of damage to these components, thereby allowing the display device 1 to have a longer service life. For example, the housing 11 can be made of plastic or metal. In this embodiment, the material of the housing 11 is not specifically limited.

[0046] The display module can be at least one of CRT (Cathode Ray Tube) display, LED (Light-Emitting Diode) display, LCD (Liquid Crystal Display) display, and OLED (Organic Light-Emitting Diode) display. Of course, in other embodiments, the display module can also be in other forms. In this application embodiment, the specific form of the display module is not limited.

[0047] The touch cover 12 and the display module are stacked on the housing 11.

[0048] The touch detection circuit 2 is disposed on the touch cover plate 12 and is electrically connected to the circuit board.

[0049] Referring to Figures 1-4, in one embodiment, the touch detection circuit 2 includes a piezoelectric ceramic sensor 21, a conductive element 22, a detection circuit 24, a compensation circuit 26, and a controller 25.

[0050] The piezoelectric ceramic sensor 21 includes a conductive substrate 211, a positive piezoelectric layer 212, a ceramic body 213, and a negative piezoelectric layer 214. The conductive substrate 211 is bonded to the touch cover plate 12. The positive piezoelectric layer 212 is disposed on the side of the ceramic body 213 facing away from the conductive substrate 211, and the negative piezoelectric layer 214 is disposed on the side of the ceramic body 213 facing the conductive substrate 211. The negative piezoelectric layer 214 is connected to the conductive substrate 211. A high-modulus adhesive can be used to bond the conductive substrate 211 to the touch cover plate 12, thereby improving the connection stability between the touch cover plate 12 and the piezoelectric ceramic sensor 21, reducing the probability of the piezoelectric ceramic sensor 21 detaching from the touch cover plate 12, and thus improving the accuracy of the piezoelectric ceramic sensor 21 in detecting vibration and pressure signals from the touch cover plate 12. For example, the high-modulus adhesive can be, but is not limited to, epoxy adhesive or acrylic adhesive. In other embodiments, the high-modulus adhesive can also be other forms. In this embodiment of the application, no specific limitations are imposed.

[0051] It is understood that the touch detection circuit 2 may include multiple piezoelectric ceramic sensors 21, with adjacent piezoelectric ceramic sensors 21 spaced apart. The multiple piezoelectric ceramic sensors 21 disposed around the touch cover plate 12 can improve the accuracy of the piezoelectric ceramic sensors 21 in detecting vibration and pressure signals from the touch cover plate 12. In this embodiment, there are no specific limitations on the number of piezoelectric ceramic sensors 21 or their arrangement around the touch cover plate 12.

[0052] Referring to Figures 1 and 2, in one embodiment, since the time required for the adhesive to solidify after applying it between the conductive substrate 211 and the touch cover plate 12 is relatively long, in order to improve the production efficiency of the display device 1, the conductive substrate 211 and the touch cover plate 12 can be bonded together with adhesive tape to position the conductive substrate 211 and the touch cover plate 12. This reduces the probability of the conductive substrate 211 moving relative to the touch cover plate 12 after the tooling fixture is removed, thereby improving the production efficiency of the display device 1.

[0053] Furthermore, the positive piezoelectric layer 212 and the negative piezoelectric layer 214 can be piezoelectric silver layers to improve their conductivity. To reduce the oxidation rate of the positive piezoelectric layer 212, a liquid photoresist is also coated on the surface of the positive piezoelectric layer 212 of the piezoelectric ceramic sensor 21 to reduce the probability of the positive piezoelectric layer 212 coming into direct contact with air, thereby reducing the oxidation rate of the positive piezoelectric layer 212. Moreover, the liquid photoresist is an insulating material and can form an insulating layer 215 on the surface of the positive piezoelectric layer 212.

[0054] In this embodiment, the conductive substrate 211 and the touch cover plate 12 can be connected by a conductive element 22. The conductive element 22 is disposed on the side of the insulating layer 215 away from the positive piezoelectric layer 212 and connected to the touch cover plate 12, so that the piezoelectric ceramic sensor 21 can be sandwiched between the touch cover plate 12 and the conductive element 22, which can also achieve the pre-fixation of the piezoelectric ceramic sensor 21.

[0055] Furthermore, when the conductive element 22 comes into contact with the conductive substrate 211, the conductive element 22 will conduct electricity with the conductive substrate 211. Thus, the conductive substrate 211 and the conductive element 22 can be used to wrap the piezoelectric ceramic sensor 21 to form a wrapping shielding layer, thereby improving the ability of the piezoelectric ceramic sensor 21 to resist electromagnetic interference and thus improving the detection accuracy of the piezoelectric ceramic sensor 21.

[0056] It is understood that the conductive component 22 can be conductive adhesive tape, which is bonded to the side of the insulating layer 215 facing away from the positive piezoelectric layer 212 and to the touch cover plate 12 to achieve pre-fixation of the piezoelectric ceramic sensor 21. Since the conductive adhesive tape can be deformed arbitrarily, the contact area between the conductive adhesive tape and the piezoelectric ceramic sensor 21 can be increased to improve the connection stability between the conductive adhesive tape and the piezoelectric ceramic sensor 21, thereby improving the connection stability between the piezoelectric ceramic sensor 21 and the touch cover plate 12 and reducing the probability of the piezoelectric ceramic sensor 21 moving relative to the touch cover plate 12.

[0057] In other embodiments, the conductive element 22 can also be a metal element. The metal element is disposed on the side of the insulating layer 215 away from the positive piezoelectric layer 212 and is bonded to the touch cover plate 12. Similarly, the metal element and the conductive substrate 211 can be used to wrap the piezoelectric ceramic sensor 21 to form a shielding layer, thereby improving the ability of the piezoelectric ceramic sensor 21 to resist electromagnetic interference and thus improving the detection accuracy of the piezoelectric ceramic sensor 21. In the embodiments of this application, the specific form of the conductive element 22 is not limited.

[0058] Furthermore, the conductive element 22 can at least completely cover the side of the insulating layer 215 away from the positive piezoelectric layer 212, which can further improve the ability of the positive piezoelectric layer 212 to resist electromagnetic interference.

[0059] Referring to Figures 1 and 3, the touch detection circuit 2 further includes a thermal insulation structure 23. The thermal insulation structure 23 covers the side of the conductive element 22 facing away from the piezoelectric ceramic sensor 21, thereby stabilizing the temperature of the piezoelectric ceramic sensor 21 and reducing the impact of external temperature changes on the sensor, thus improving the detection accuracy of the piezoelectric ceramic sensor 21. Exemplarily, the material of the thermal insulation structure 23 may include at least one of expanded polystyrene (EPS), polyurethane foam (PU), rubber and plastic insulation materials, rock wool, glass wool, and silicate insulation materials. In other embodiments, the thermal insulation structure 23 may also be made of other materials.

[0060] It is understandable that the conductive component 22 can be integrally formed with the thermal insulation structure 23, and the assembly of the conductive component 22 and the thermal insulation structure 23 can be achieved through one installation. Compared with the separate assembly of the conductive component 22 and the thermal insulation structure 23, the assembly steps can be reduced and the assembly efficiency of the conductive component 22 and the thermal insulation structure 23 can be improved, thereby improving the production efficiency of the display device 1.

[0061] Referring to Figures 1-4, in one embodiment, the detection circuit 24 is electrically connected to the conductive element 22 and the piezoelectric ceramic sensor 21, respectively, and the controller 25 is connected to the detection circuit 24. The detection circuit 24 is used to convert the charge change generated by the piezoelectric ceramic sensor 21 into a voltage signal, and the controller 25 is used to acquire the vibration signal and / or pressure signal of the touch cover 12 based on the voltage signal. When the user touches the touch cover 12, the piezoelectric ceramic sensor 21 converts the stress deformation into a change in charge. The detection circuit 24 acquires the change in charge and converts it into a voltage signal. The controller 25 can acquire the vibration signal and / or pressure signal of the touch cover 12 based on the voltage signal, thereby acquiring the touch point and the material of the touch object based on the vibration signal and pressure signal.

[0062] Referring to Figures 1-4, in one embodiment, the positive terminal of the detection circuit 24 is electrically connected to the positive piezoelectric layer 212, and the negative terminal of the detection circuit 24 is electrically connected to the conductive element 22; it is used to convert the change in charge generated between the positive piezoelectric layer 212 and the negative piezoelectric layer 214 of the piezoelectric ceramic sensor 21 into a voltage signal; the controller 25 is connected to the detection circuit 24 and is used to obtain the vibration signal and pressure signal on the touch cover 12 according to the voltage signal, thereby obtaining the touch point and the material of the touch object for touching the touch cover 12 according to the vibration signal and pressure signal.

[0063] For example, the pen tip is made of a softer foamed PE material, the pen tail is made of a hard solid plastic material, and the finger is made of an even softer material. The vibration signal frequencies generated when different materials come into contact with the touch cover 12 are different. By analyzing the frequency components of the received vibration signal, the controller 25 can determine whether the current contact object is the pen tip, the pen tail, or a finger.

[0064] It is understood that in other embodiments, the positive terminal of the detection circuit 24 is electrically connected to the positive piezoelectric layer 212, and the negative terminal of the detection circuit 24 can also be electrically connected to the conductive element 22 through the negative piezoelectric layer 214.

[0065] It is understood that in other embodiments, the positive terminal of the detection circuit 24 is electrically connected to the positive piezoelectric layer 212, and the negative terminal of the detection circuit 24 can also be electrically connected to the conductive element 22 through the conductive substrate 211.

[0066] In this embodiment, when a user touches the touch cover 12, the piezoelectric ceramic sensor 21 converts the vibration signal and pressure signal into the change in charge between the positive piezoelectric layer 212 and the negative piezoelectric layer 214. The detection circuit 24 converts the change in charge generated by the piezoelectric ceramic sensor 21 into a digital detection signal so that the controller 25 can obtain the detection signal to obtain the touch point of the user touching the touch cover 12 and the material of the touched object.

[0067] Furthermore, after the controller 25 acquires the detection signal, it can control the compensation circuit 26 to output a compensation charge to the positive piezoelectric layer 212 of the piezoelectric ceramic sensor 21, so that the charge between the positive piezoelectric layer 212 and the negative piezoelectric layer 214 of the piezoelectric ceramic sensor 21 is equal to the preset charge, thereby restoring the piezoelectric ceramic sensor 21 to its initial state. This allows the piezoelectric ceramic sensor 21 to convert the vibration signal and pressure signal into a change in charge for the second time, thereby improving the accuracy of the charge conversion of the piezoelectric ceramic sensor 21 and the accuracy of the detection signal acquired by the controller 25, thus improving the accuracy of the judgment of the touch point of the touch cover 12 and the material of the touched object.

[0068] Furthermore, by using the conductive substrate 211 and the conductive element 22 to wrap the piezoelectric ceramic to form a shielding layer, the ability of the piezoelectric ceramic sensor 21 to resist electromagnetic interference is improved, thereby improving the detection accuracy of the piezoelectric ceramic sensor 21. This simplifies the circuit design of the touch detection circuit 2, reduces the cost of the touch detection circuit 2, and thus reduces the cost of the display device 1.

[0069] Understandably, the piezoelectric ceramic sensor 21 converts vibration and pressure signals into changes in charge between the positive piezoelectric layer 212 and the negative piezoelectric layer 214. The detection circuit 24 can convert these changes in charge into digital detection signals. After the controller 25 receives the detection signals, it can control the compensation circuit 26 to output compensation charge to the piezoelectric ceramic sensor 21, ensuring that the charge between the positive piezoelectric layer 212 and the negative piezoelectric layer 214 of the piezoelectric ceramic sensor 21 equals the preset charge. This allows the process of the piezoelectric ceramic sensor 21 returning to its initial state to be continuously and cyclically executed, ensuring that the change in charge of the piezoelectric ceramic sensor 21 is more accurate when the user touches the touch cover 12, thereby improving the accuracy of judging the touch point and the material of the touched object.

[0070] In this embodiment of the application, there is no specific limitation on the interval duration of the above-mentioned continuous execution of the loop, which can be selected according to design requirements.

[0071] Understandably, since the controller 25 can periodically acquire detection signals and output compensation charge to the piezoelectric ceramic sensor 21 through the compensation circuit 26, the charge of the piezoelectric ceramic sensor 21 is made equal to the preset charge, thereby restoring the piezoelectric ceramic sensor 21 to its initial state. Therefore, the measurement range of the touch detection circuit 2 can be increased, thereby expanding the applicability of the touch detection circuit 2.

[0072] For example, the pen tip is made of a softer foamed PE material, the pen tail is made of a hard solid plastic material, and the finger is made of an even softer material. The vibration signal frequencies generated when different materials come into contact with the touch cover 12 are different. By analyzing the frequency components of the received vibration signal, the controller 25 can determine whether the current contact object is the pen tip, the pen tail, or a finger.

[0073] Referring to Figures 4 and 5, in one embodiment, the detection circuit 24 includes a charge integration circuit 241, a non-inverting amplifier circuit 242, and an analog-to-digital converter circuit 243. The charge integration circuit 241 is connected to the conductive element 22 and the positive piezoelectric layer 212. The input terminal of the non-inverting amplifier circuit 242 is connected to the output terminal of the charge integration circuit 241, the input terminal of the analog-to-digital converter circuit 243 is connected to the output terminal of the non-inverting amplifier circuit 242, and the output terminal of the analog-to-digital converter circuit 243 is connected to the controller 25.

[0074] When a user touches the touch cover 12, the piezoelectric ceramic sensor 21 converts the vibration signal and pressure signal into the change in charge between the positive piezoelectric layer 212 and the negative piezoelectric layer 214. The change in charge is converted into a voltage signal by the charge integration circuit 241. The voltage signal is amplified by the in-phase amplifier circuit 242 and then converted into a digital detection signal by the analog-to-digital converter circuit 243, so that the controller 25 can obtain the detection signal and obtain the touch point of the user touching the touch cover 12 and the material of the touched object.

[0075] Understandably, the controller 25 can filter the detection signal output by the analog-to-digital converter circuit 243 using a digital filter, and then sample the voltage signal output by the non-inverting amplifier circuit 242 via the analog-to-digital converter (ADC). This can reduce the data processing burden of the controller 25 and improve the data processing accuracy of the controller 25.

[0076] Referring to Figures 4 and 5, in one embodiment, the charge integrating circuit 241 includes a first amplifier A1, a first capacitor C1, and a first resistor R1. The inverting input terminal of the first amplifier A1 is connected to the positive piezoelectric layer 212, the non-inverting input terminal of the first amplifier A1 is connected to the conductive element 22, and the non-inverting input terminal of the first amplifier A1 is used to connect to a power supply. The positive power supply terminal of the first amplifier A1 is used to connect to a power supply, the negative power supply terminal of the first amplifier A1 is grounded, and the output terminal of the first amplifier A1 is connected to the output terminal of the charge integrating circuit 241. The first plate of the first capacitor C1 is connected to the inverting input terminal of the first amplifier A1, and the second plate of the first capacitor C1 is connected to the output terminal of the first amplifier A1. The first end of the first resistor R1 is connected to the first plate of the first capacitor C1, and the second end of the first resistor R1 is connected to the second plate of the first capacitor C1.

[0077] The first resistor R1 provides input bias current to the first amplifier A1 to ensure its normal operation. When abnormal charge enters the first capacitor C1, the first capacitor C1 discharges through the first resistor R1, eliminating the impact of the abnormal charge on the voltage across the first capacitor C1. This reduces the impact of the abnormal charge on the output signal of the first amplifier A1, improving the accuracy of the output voltage signal. The first capacitor C1 is an integrating capacitor and forms an analog integrator with the first amplifier A1. The analog integrator transfers and accumulates the change in charge generated by the piezoelectric ceramic sensor 21 into the first capacitor C1, thereby realizing the change in input charge and outputting a voltage signal. The voltage signal at the output of the first amplifier A1 is linearly correlated with the change in charge between the two plates of the first capacitor C1.

[0078] In this embodiment, the voltage of the power supply connected to the non-inverting input terminal of the first amplifier A1 can be a first voltage, and the voltage of the power supply connected to the positive power supply terminal of the first amplifier A1 can be a second voltage. The first voltage can be half of the second voltage, so that the positive signal acquisition range and the negative signal acquisition range of the first amplifier A1 are both large, thereby increasing the range of the input signal of the first amplifier A1 and improving the charge input range of the charge integration circuit 241, thus improving the performance of the charge integration circuit 241. It is understood that the first voltage can also be one-quarter or one-eighth of the second voltage, which can be selected according to the actual circuit requirements. In this embodiment, no specific limitation is made.

[0079] It is understood that, in the embodiments of this application, the voltage value corresponding to the preset charge amount is the voltage value of the first voltage.

[0080] Referring to Figures 2-4, it can be understood that in order to ensure a stable connection between the inverting input terminal of the first amplifier A1 and the positive piezoelectric layer 212, an insulating sealant 216 can be applied at the contact point. The insulating sealant 216 can prevent the positive piezoelectric layer 212 from conducting through the contact point with the conductive component 22, thereby improving the accuracy of the piezoelectric ceramic sensor 21 in converting vibration and pressure signals into changes in the amount of charge between the positive piezoelectric layer 212 and the negative piezoelectric layer 214, and improving the accuracy of judging the touch point of the touch cover 12 and the material of the touched object.

[0081] Referring to Figures 4 and 5, in one embodiment, the charge integration circuit 241 further includes a second resistor R2. The first end of the second resistor R2 is connected to the positive piezoelectric layer 212, and the second end of the second resistor R2 is connected to the inverting input terminal of the first amplifier A1. The second resistor R2 is used to divide the voltage corresponding to the amount of charge entering the inverting input terminal of the first amplifier A1 to limit the bandwidth of the charge integration circuit 241, and can adjust the phase of the charge integration circuit 241, thereby improving the loop stability of the charge integration circuit 241.

[0082] Referring to Figures 4 and 5, in one embodiment, the non-inverting amplifier circuit 242 includes a third resistor R3, a fourth resistor R4, a second amplifier A2, and a fifth resistor R5. The first end of the third resistor R3 is connected to the input terminal of the non-inverting amplifier circuit 242; the first end of the fourth resistor R4 is used to connect to the power supply; the non-inverting input terminal of the second amplifier A2 is connected to the second end of the third resistor R3, the inverting input terminal of the second amplifier A2 is connected to the second end of the fourth resistor R4, the positive power supply terminal of the second amplifier A2 is used to connect to the power supply, the negative power supply terminal of the second amplifier A2 is grounded, and the output terminal of the second amplifier A2 is connected to the output terminal of the non-inverting amplifier circuit 242; the first end of the fifth resistor R5 is connected to the inverting input terminal of the second amplifier A2, and the second end of the fifth resistor R5 is connected to the output terminal of the second amplifier A2. The non-inverting amplifier circuit 242, composed of the third resistor R3, the fourth resistor R4, the second amplifier A2, and the fifth resistor R5, amplifies the voltage signal output by the charge integrating circuit 241 to improve the accuracy of the detection signal acquired by the controller 25.

[0083] Furthermore, the non-inverting amplifier circuit 242 also includes a second capacitor C2. The first plate of the second capacitor C2 is connected to the inverting input terminal of the second amplifier A2, and the second plate of the second capacitor C2 is connected to the output terminal of the second amplifier A2. The second capacitor C2 can present a low impedance to high-frequency noise, and the amplification factor of high-frequency noise can be selectively reduced through the fifth resistor R5. This allows the non-inverting amplifier circuit 242 to have a better amplification effect on low-frequency signals, thereby improving the accuracy of the detection signal acquired by the controller 25.

[0084] Referring to Figures 4 and 5, in one embodiment, the non-inverting amplifier circuit 242 further includes a sixth resistor R6. The first end of the sixth resistor R6 is connected to the output terminal of the second amplifier A2, and the second end of the sixth resistor R6 is connected to the output terminal of the non-inverting amplifier circuit 242. The sixth resistor R6 can limit the current of the voltage signal output from the output terminal of the second amplifier A2, thereby reducing the probability of the analog-to-digital converter circuit 243 and the controller 25 being damaged by high current. This allows the analog-to-digital converter circuit 243 and the controller 25 to have a longer service life, which in turn allows the touch detection circuit 2 to have a longer service life.

[0085] Referring to Figures 4 and 5, in one embodiment, the analog-to-digital converter circuit 243 includes a first comparator A3. The non-inverting input of the first comparator A3 is connected to the input of the analog-to-digital converter circuit 243, the inverting input of the first comparator A3 is connected to a power supply, and the output of the first comparator A3 is connected to the output of the analog-to-digital converter circuit 243. Using the first comparator A3, the amplified voltage signal output from the second amplifier A2 can be converted into a digital signal, so that the controller 25 can receive the corresponding digital detection signal, thereby obtaining the touch point of the touch cover 12 and the material of the touched object.

[0086] It is understood that, in this embodiment, the first comparator A3 can be a 1-bit quantizer to convert the continuously amplified voltage signal into a PDM (Pulse Density Modulation) signal, thereby converting the voltage signal into a detection signal so that the controller 25 can filter and sample the detection signal. In other embodiments, the analog-to-digital converter 243 may also include a Schmitt trigger to utilize the Schmitt trigger as a 1-bit quantizer. In this embodiment, the specific form of the analog-to-digital converter 243 is not limited.

[0087] Understandably, the controller 25 can also periodically acquire the detection signal output by the 1-bit quantizer through the sampler, which can further reduce the data processing burden of the controller 25, and then perform digital filtering processing to further improve the signal-to-noise ratio.

[0088] It is understood that the sampler can be a digital sampler, which can be located within the controller 25 or be a sampling module. In this embodiment, the specific form of the sampler is not limited.

[0089] Referring to Figures 4 and 5, in one embodiment, the compensation circuit 26 includes a Schmitt trigger A4. The input terminal of the Schmitt trigger A4 is connected to the input terminal of the compensation circuit 26, and the output terminal of the Schmitt trigger A4 is connected to the output terminal of the compensation circuit 26. After the controller 25 receives the detection signal, it sends a compensation signal to the input terminal of the Schmitt trigger A4 according to the detection signal, so that the Schmitt trigger A4 outputs a compensation charge to the positive piezoelectric layer 212 of the piezoelectric ceramic sensor 21 according to the compensation signal, so that the charge between the positive piezoelectric layer 212 and the negative piezoelectric layer of the piezoelectric ceramic sensor 21 is equal to the preset charge, thereby restoring the piezoelectric ceramic sensor 21 to its initial state.

[0090] Referring to Figures 4 and 5, in one embodiment, the compensation circuit 26 further includes a seventh resistor R7. The first end of the seventh resistor R7 is connected to the output of the Schmitt trigger A4, and the second end of the seventh resistor R7 is connected to the output of the compensation circuit 26. By using the seventh resistor R7, the probability of a large current entering the positive piezoelectric layer 212 of the piezoelectric ceramic sensor 21 can be reduced, thereby reducing the probability of damage to the piezoelectric ceramic sensor 21 and enabling the piezoelectric ceramic sensor 21 to have a longer service life.

[0091] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0092] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A touch detection circuit, wherein, The touch detection circuit includes a piezoelectric ceramic sensor, a conductive component, a detection circuit, a compensation circuit, and a controller; The piezoelectric ceramic sensor is disposed on the touch cover plate, the conductive element covers the piezoelectric ceramic sensor and is electrically connected to the piezoelectric ceramic sensor, the detection circuit is electrically connected to the conductive element and the piezoelectric ceramic sensor respectively, the compensation circuit is connected to the piezoelectric ceramic sensor, the input terminal of the controller is connected to the detection circuit, and the output terminal of the controller is connected to the compensation circuit. The detection circuit is configured to acquire the charge change of the piezoelectric ceramic sensor and output a digital detection signal; the compensation circuit is configured to output a compensation charge to the piezoelectric ceramic sensor so that the charge of the piezoelectric ceramic sensor is equal to a preset charge; the controller is configured to receive the detection signal and acquire the vibration signal and / or pressure signal of the touch cover plate according to the detection signal, and the controller is further configured to control the compensation circuit to output the compensation charge to the piezoelectric ceramic sensor according to the detection signal.

2. The touch detection circuit of claim 1, wherein, The piezoelectric ceramic sensor includes: a conductive substrate, a positive piezoelectric layer, a ceramic body, a negative piezoelectric layer, and an insulating layer. The conductive substrate is bonded to the touch cover plate. The positive piezoelectric layer is disposed on the side of the ceramic body away from the conductive substrate. The insulating layer at least covers the side of the positive piezoelectric layer away from the ceramic body. The negative piezoelectric layer is disposed on the side of the ceramic body facing the conductive substrate and is connected to the conductive substrate. A portion of the conductive element covers the side of the insulating layer away from the positive piezoelectric layer, and another portion of the conductive element covers the conductive substrate and is electrically connected to the conductive substrate. The detection circuit is electrically connected to the conductive element and the positive piezoelectric layer respectively, and the compensation circuit is connected to the positive piezoelectric layer.

3. The touch detection circuit of claim 2, wherein, The positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive component. Alternatively, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive component through the negative piezoelectric layer; Alternatively, the positive terminal of the detection circuit is electrically connected to the positive piezoelectric layer, and the negative terminal of the detection circuit is electrically connected to the conductive component through the conductive substrate.

4. The touch detection circuit of claim 2, wherein, The detection circuit includes: A charge integration circuit, connected to the conductive element and the positive piezoelectric layer, is configured to output a voltage signal; A non-inverting amplifier circuit, wherein the input terminal of the non-inverting amplifier circuit is connected to the output terminal of the charge integrating circuit, and is configured to amplify the voltage signal; and An analog-to-digital converter circuit is provided, wherein the input terminal of the analog-to-digital converter circuit is connected to the output terminal of the non-inverting amplifier circuit, and the output terminal of the analog-to-digital converter circuit is connected to the controller, and is configured to convert the amplified voltage signal into the digital form of the detection signal.

5. The touch detection circuit of claim 4, wherein, The charge integration circuit includes: A first amplifier, wherein the inverting input terminal of the first amplifier is connected to the positive piezoelectric layer, the non-inverting input terminal of the first amplifier is connected to the conductive element, and the non-inverting input terminal of the first amplifier is configured to be connected to a power supply, the positive power supply terminal of the first amplifier is configured to be connected to a power supply, the negative power supply terminal of the first amplifier is grounded, and the output terminal of the first amplifier is connected to the output terminal of the charge integration circuit. A first capacitor, wherein the first plate of the first capacitor is connected to the inverting input terminal of the first amplifier, and the second plate of the first capacitor is connected to the output terminal of the first amplifier; and A first resistor, the first end of which is connected to the first plate of the first capacitor, and the second end of which is connected to the second plate of the first capacitor.

6. The touch detection circuit of claim 5, wherein, The charge integration circuit further includes: The second resistor has its first end connected to the positive piezoelectric layer and its second end connected to the inverting input of the first amplifier.

7. The touch detection circuit of claim 4, wherein, The in-phase amplifier circuit includes: The third resistor, the first end of which is connected to the input terminal of the non-inverting amplifier circuit; The fourth resistor, wherein the first end of the fourth resistor is configured to be connected to a power supply; A second amplifier, wherein the non-inverting input terminal of the second amplifier is connected to the second terminal of the third resistor, the inverting input terminal of the second amplifier is connected to the second terminal of the fourth resistor, the positive power supply terminal of the second amplifier is connected to the power supply, the negative power supply terminal of the second amplifier is grounded, and the output terminal of the second amplifier is connected to the output terminal of the non-inverting amplifier circuit; and The fifth resistor has its first end connected to the inverting input terminal of the second amplifier and its second end connected to the output terminal of the second amplifier.

8. The touch detection circuit as described in claim 7, wherein, The in-phase amplifier circuit further includes: A second capacitor, wherein the first plate of the second capacitor is connected to the inverting input terminal of the second amplifier, and the second plate of the second capacitor is connected to the output terminal of the second amplifier; and / or, The sixth resistor has its first end connected to the output terminal of the second amplifier and its second end connected to the output terminal of the non-inverting amplifier circuit.

9. The touch detection circuit as described in claim 4, wherein, The analog-to-digital conversion circuit includes: A first comparator has its non-inverting input connected to the input of the analog-to-digital converter circuit, its inverting input connected to the power supply, and its output connected to the output of the analog-to-digital converter circuit.

10. The touch detection circuit as described in claim 1, wherein, The compensation circuit includes: A Schmitt trigger is provided, wherein the input terminal of the Schmitt trigger is connected to the input terminal of the compensation circuit, and the output terminal of the Schmitt trigger is connected to the output terminal of the compensation circuit.

11. The touch detection circuit as described in claim 10, wherein, The compensation circuit further includes: The seventh resistor has its first end connected to the output of the Schmitt trigger and its second end connected to the output of the compensation circuit.

12. A display device, wherein, include: case; The display module is connected to the housing. The touch cover plate is stacked on the housing along with the display module; The circuit board is disposed within the housing; as well as The touch detection circuit as described in claim 1 is disposed on the touch cover plate and electrically connected to the circuit board.

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